Starch cooking apparatus and method



March 31, 1953 F. H. MARTIN STARCH COOKING APPARATUS AND METHOD Filed Sept. 2; 1950 INVENTOR- Fl/RMAN H. MAR TIN M, 5 ATTQRIVf'Vv-T Patented Mar. 31, 1953 UNITED STATES PATENT STABGH 'GOOKING APPARATUS -METHOD -Furman Martin, Lancaster, "$50., assignor'to Springs Cottn ,Mills, a corporation of south Caro na Applieation septem 2, 1,950 e ai N9 18,2;2Q5

(cram-gag!) =I-his invention relates to the preparation of starch pastes, and more particularly to an improved apparatus and method for cooking starch ..pastes for use in slashing textile yarns.

Raw starch is insoluble in water and is normal- 1y solubilized by boiling, which causes the individual cell walls to burst and form the characteristic milky starch paste, the physical properties of which are dependent to a large extent on the manner and conditions of preparation. For

yarn is subjected'to relatively severe tensional and flexing stressesand to a varying amount of abrasion, and in order to provide a yarn that will withstand these stresses and abrasion without excessive breakage, it is necessary to bind the fibre strands together with a strong, yet flexible protective sheath or film. To be effective, this film must be at or close to the yarn surface so that it will bind the loosely protruding fibres into the film and thereby prevent them from being worn off by abrasion,and so that it will provide a reasonably continuous film over the nonprotruding surface fibres by which they are prevented from raising up or otherwise becoming separated from the bodyof the yarn. Also, this film should be placed consistently in theouter surface layers of the yarn in such a manner as to leave a core of unbound fibre in the center of the yarn, as a core of this sort substantially improves the handling qualities of the slashed or sized yarn, apparently because it is less rigid and acts as a yielding or bending element in the yarn.

Tests have shown that the location of starch sizing film within the surface layers of the yarn is dependent upon several factors, among which .are the yarn size, yarn density, speed of slashing and the temperatureand viscosity of the size solution. With the exception of the viscosity, all

these factors can be maintained reasonably constant. However, changes in the viscosity of the size solution may account for considerable variation in the percentage of size pick up and the distribution of the sizewithin the yarn strands. In the past, it has been general practice to assume that by cooking the starch at a fixed temperature for a given length of time ata fixed pI-Land by using definite amounts of starch and water, a product of constant viscosity would be obtained. Unfortunately, :this is not: true, since variations ,in. thesstarch solubility, for example, can result it in d va a 11th?Viscosity,.lihqp f dllfli- Thus it has been found, actual vpracticcthat ,becauseof these variations albatch of starchmav not break down during .the allQbtfidcgokingperiod, while other batches may, break .down too fast and go to waterisothat .theyghave tolbfl discarded toavoid the danger of mak l bad. warps. S me p these e bat h s m so u deup n Whe her. ehe 'bfien' oo thi or teet n- In accordance with the present invention these ,difiiculties heretofore ;encountered in preparing thestarchpasteor size solutionjor slashing textile yarns are obviatedbyan improved apparatus and method for cooking the starch by Whichthe uniformity of the product-can be controlled very closely, and by which the cooking operation is carried out in a particularlyeffective manner and in a considerably shorter time than has been possible with previous methods.

Briefly described, the present invention contemplates the use of a slurry vat to contain the starch batch to be cooked, a-separate cooking chamber arranged for the introduction of live steam during the cooking operation, and pumping means for recirculating a starch slurry from the vat through the cooking chamber. By this anrangement it is possible toprovide for rapid recirculation of the batchfrom'the vat through the cooking chamber, and since the entire batch may thus be recirculated continuously,ga much larger volume of live steam can be'introduced inxthe slurry may be regulated according to the present invention, as will be explained more in detail presently, to maintain a pressure-in the cooking chamber which not only increases the rated the cooking reaction but also tends to explode the heated and swollen starch granules as they are released from this pressure upon return to the slurry vat. This effect has the important advantage of greatly facilitating the-production :of :a smooth solution of the starch particles. Examination of a dried starch film prepared in accordance with the present invention shows exceptionaltransparency, which is a clear indication of smaller and fewer suspended particles and 1 much more of-a true-chemicahsolution.

Also, it should be noted that the cooking operation may be readily controlled according to the present invention to terminate the cooking cycle when a predetermined viscosity has been reached so that a finished product may be consistently obtained having a viscosity level fully as uniform as the sensitivity of practical measuring equipment will allow.

The present invention is described further below in connection with the accompanying drawing in which the single figure is a more or less schematic representation of a starch cooking apparatus arranged in accordance with the invention.

As shown in the drawing this apparatus comprises a slurry vat or kettle 2 of suitable capacity for containing a batch of starch, as at 4, to be cooked. The vat 2 is open to the atmosphere as at the access door 6 and may be otherwise adapted in any convenient manner (not shown) f for introduction of the starch batch and removal .of the cooked starch solution.

The vat 2 is fitted at its bottom level with a drain line 8 running to the inlet iii of a pump 12 driven by a motor unit It. The outlet it of this pump i2 is in turn connected to one end of a closed cooking chamber l8, from the other end of which a return line 29 leads to the top of the vat 2 and is arranged to discharge as an open jet therein. Operation of the pump 12 accordingly results in recirculating the starch batch '4 from the vat 2 through the cooking chamber i8.

To provide for cooking the starch a steam supply line 22 is arranged to run to the cooking chamber 18, and to extend therein in a perforated length as at 24 so that live steam may be intro duced as the starch batch is recirculated. Preferably, the cooking chamber I8 is arranged with an elongated form, as shown in the drawing, the

cross section of which is enough larger than the outlet 16 of the pump I2 at the least to allow disposition of the extending perforated length 24 of steam line 22 centrally within the cooking chamber i8 and for substantially its entire length.

With this arrangement, it is possible to carry out the cooking operation in a very rapid and 'efiicient manner. For example, according to conventional practice cooking kettles of 200 gallon capacity are usually employed, and about two hours is necessary to complete the cooking cycle.

'much larger volume of steam may be introduced in the cooking chamber I8 than is feasible with a conventional kettle because of the danger of trapping excessive steam in the bottom of the kettle and causing boil-over. On the other hand, the apparatus of the present invention may be readily arranged to recirculate the complete contents of the vat 2 through the cooking cham- -ber I8 as rapidly as every one to two minutes,

so that the entire starch batch is recirculated continuously through the cooking chamber 18 which holds substantially all of the steam introduced, while any steam entrained in the return line 20 is merely released to the atmosphere at .the top of vat 2.

Another important feature of the apparatus of the present invention is that the return line 20 may be arranged to throttle the recirculating flow from the pump [2 and thereby induce pressure in the cooking chamber I8 at a desired level, and by employing a pressure in the chamber 58 of several times atmospheric pressure the rate of the cooking reaction is advantageously increased which further decreases the cooking time. Preferably, the return line 20 is fitted with an adjustable orifice as by a valve 26 so that throttling of the return line 20 may be regulated easily to obtain a suitable pressure in the cooking chamber [8.

Also, it should be noted again that the cooking time is additionally lessened by the arrangement of the return line 28 to discharge at the top of vat 2 as an open jet, which gives the heated and swollen starch granules a chance to explode as they are released to atmospheric pressure. In addition, the jet from the return line 29 serves the purpose of agitationg the contents of vat 2 throughout the entire cooking operation and thereby eliminates the necessity for providing any mechanical agitating means as is usually done. In order to adapt the return line 20 further for this purpose, it may be fitted with a positionable nozzle as at 28 so that the returning jet of size solution as indicated at 3! may be directed to the best advantage for maintaining the contents of vat 2 agitated.

The apparatus of the present invention is also well adapted for regulation by suitable automatic controls so that the cooking operation may be carried out with dependable and uniform results. The cooking operations, for example, should be carried out at a temperature below 212 F.; a usual cooking temperature is 210 F. To insure maintaining the temperature within this necessary limit, the vat 2 ma be fitted with a temperature-sensitive element, such as a thermocouple as at 32, arranged so that it is exposed in the vet 2 at a level that is submerged during the cooking operation, and connected as at 34 for actuating a control valve 36 in the steam line 22 and thereby throttling the steam supply so that the temperature of the starch batch being handled is maintained at a proper level.

Also, as has been previously pointed out, a close control of the viscosity of the cooked size solution is necessary for satisfactory use in the slashing of textile yarn. Provision for obtaining the necessary uniformity in this respect is made according to the present invention by disposing a viscosity sensing element as at 38 at a submerged level in the vat 2 (i. e., as disclosed in U. S. Patent No. 2,491,389), and connecting this sensing element 38 through a recording controller 40 which may be set to actuate a control valve 42 and a switch unit 44, for closing the steam supply line 22 and stopping the pump motor id, and thereby terminating the cooking operation when a predetermined viscosity has been attained.

The connection from the recording controller 40 to the control valve 42 should preferably run through a manually operated switch as at 46 so that the pump motor M can be operated for precooking agitation with the steam line 22 closed if desired, and a manually operated valve should be disposed as at 48 in the steam line 22 for throttling the steam supply appropriately to the requirements of the apparatus.

I claim:

1. A starch cooking apparatus comprising a slurry vat for containing a batch of starch to be cooked, said vat being open to the atmosphere,

an elongated cooking chamber separate from said vat and closed to the atmosphere, a perforated steam supply line extending in said cooking chamber for substantially its entire length, a pump having its intake connected at the bottom level of said vat and its outlet to one end of said cooking chamber, a return line leading from the other end of said cooking chamber to the top of said vat and arranged to discharge openly therein, and an adjustable orifice in said return line for throttling said line against said pump and thereby inducing pressure at a desired level in said cooking chamber during a cooking operation.

2. A starch cooking apparatus comprising a slurry vat for containing a batch of starch to be cooked, said vat being open to the atmosphere, a pump having its intake connected at the bottom level of said vat, an elongated cooking chamber connected at one end to the outlet of said pump and closed to the atmosphere, a perforated steam supply line extending centrally in said cooking chamber for substantially its entire length, a return line leading from the other end of said cooking chamber to the top of said vat and terminating as an open jet therein, means for driving said pump whereby a starch batch may be recirculated from said vat through said cooking chamber, and an adjustable orifice in said return line for throttling the recirculating flow therein from said pump and thereby inducing pressure in said cooking chamber at a desired level during a cooking operation.

3. A starch cooking apparatus as defined in claim 2 and further characterized in that a temperature-sensitive element is exposed in said slurry vat at a level that is submerged during a cooking operation, and an adjustable valve means responsive to said temperature-sensitive element is disposed for controlling the flow of steam in said supply line whereby the temperature of a starch batch being handled in said apparatus may be maintained at a desired level during a cooking operation.

4. A starch cooking apparatus as defined in claim 2 and further characterized in that a viscosity sensing element is exposed in said slurry vat at a level that is submerged during a cooking operation, and an actuating means responsive to said sensing element is provided for disconnecting said pump driving means and for closing said steam supply line when a starch batch being handled in said apparatus has attained a predetermined viscosity.

5. A starch cooking apparatus as defined in claim 4 and further characterized in that manual means for disconnecting said actuating means is provided whereby said pump driving means may be operated with said steam supply line closed for precooking agitation of a starch batch.

6. The method of cooking starch which oomprises placing a starch batch to be cooked in an open container, recirculating said starch batch from said container through a separate confined space by withdrawing said starch batch from the bottom level of said container and returning it from said confined space openly in jet form at the top of said container, introducing live steam to said confined space in direct contact with said starch bat-ch during said recirculation, throttling the return of said recirculating starch batch and thereby inducing pressure in said confined space at a desired level during the cooking operation, and continuing said recirculation until said starch is cooked as desired.

7. The method of cooking starch as defined in claim 6 and further characterized in that the introduction of steam to said confined space is controlled in response to the temperature in said container of said recirculating starch batch.

8. The method of cooking starch as defined in claim 6 and further characterized in that the introduction of steam to said confined space and the recirculation of said starch batch is discontinued in response to the attainment of a predetermined viscosity for the starch batch in said container.

9. The method of cooking starch which comprises placing a starch batch to be cooked in an open container, recirculating said starch batch from said container through a separate confined space While introducing live steam to said confined space in direct contact with the starch batch being circulated therethrough, returning the circulated starch batch from said confined space openly to said open container while throttling said return and thereby inducing pressure in said confined space at a desired level during the cooking operation, and continuing said recirculation until said starch is cooked as desired.

10. Apparatus for cooking starch comprising an open slurry vat for containing a batch of starch to be cooked, a separate, closed, elongated cooking chamber, a perforated steam supply line opening into said cooking chamber and extending substantially the entire length thereof for introducing live steam therein, a drain line running from the bottom of said slurry vat, a pump having its intake connected to said drain line, a connecting line running from the outlet of said pump to one end of said cooking chamber and opening therein for recirculating a starch batch from said slurry vat through said cooking chamber in direct contact with steam introduced from said supply line, a return line running from the other end of said cooking chamber to the top of said slurry vat, said return line having a discharge opening exposed to the atmosphere in said slurry vat for releasing entrained steam therefrom, and an adjustable orifice in said return line for throttling said line against said pump and thereby inducing pressure at a desired level in said cooking chamber during a cooking operation.

FURMAN I-I. MAR'IIN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,411,934 Rankin Apr. 4, 1922 1,418,320 Miller June 6, 1922 2,174,178 Nichols Sept. 26, 1939 2,321,893 Bimpson et a1 June 15, 1943 2. 161384 Kyame Aug. 1, 1950 2,521,215 Haddeland et al. Sept. 5, 1950 FOREIGN PATENTS Number Country Date 135,590 Great Britain Nov. 27, 1919 

1. A STARCH COOKING APPARATUS COMPRISING A SLURRY VAT FOR CONTAINING A BATCH OF STARCH TO BE COOKED, SAID VAT BEING OPEN TO THE ATMOSPHERE, AN ELONGATED COOKING CHAMBER SEPARATE FROM SAID VAT AND CLOSED TO THE ATMOSPHERE, A PERFORATED STEAM SUPPLY LINE EXTENDING IN SAID COOKING CHAMBER FOR SUBSTANTIALLY ITS ENTIRE LENGTH, A PUMP HAVING ITS INTAKE CONNECTED AT THE BOTTOM LEVEL OF SAID VAT AND ITS OUTLET TO ONE END OF SAID COOKING CHAMBER, A RETURN LINE LEADING FROM THE OTHER END OF SAID COOKING CHAMBER TO THE TOP OF SAID VAT AND ARRANGED TO DISCHARGE OPENLY THEREIN, AND AN ADJUSTABLE ORIFICE IN SAID RETURN LINE FOR THROTTLING SAID LINE AGAINST SAID PUMP AND THEREBY INDUCING PRESSURE AT A DESIRED LEVEL IN SAID COOKING CHAMBER DURING A COOKING OPERATION. 